You can't get much simpler than the plot of UNSTOPPABLE. Two average joe railroad workers try to stop an unmanned runaway train carrying toxic chemicals from crashing in a highly populated area. That's about it. There's a little back story for the characters, but not much. Almost the entire movie is devoted to trying to stop the train. And that makes for a very suspenseful film that I really enjoyed.
However, it occurred to me that very, very few of the people who watch this movie would ever realize it's a high-tech, 21st Century version of the sort of yarns that used to appear all the time in the pulp RAILROAD STORIES. I have a few issues of this magazine, and it's pretty darned good. Here are a few covers.
Tower of Glass (1970)
33 minutes ago